Many motor vehicles, particularly foreign cars, can neither be towed by the bumper nor by connection to an axle. The bumper and vehicle suspension system presently found on most automobiles prohibits the former while lack of the traditional full transverse axle prevents the latter.
The patent literature and the market place are not without examples of towing slings in which either the front end or the back end of a vehicle to be towed can be raised by cradles installed under the vehicle's wheels. One such apparatus is disclosed in U.S. Pat. No. 3,897,879.
The patented device referred to above enables a towed vehicle to be lifted by the wheels and thus solves the problem of how to tow a car with-out hitching to a bumper or an axle. However, the apparatus disclosed in the patent involves not merely a wheel cradle but a rather sophisticated, complicated and not inexpensive piece of towing equipment involving a powered, extensible boom in addition to sling means.
In many instances it is desirable that wheel supporting devices be attachable to existing conventional towing rigs. In other words, despite the prior art there remains considerable room for improvement, particularly where it is desirable to adapt existing tow truck equipment to meet new demands.